Apparatus for forming subterranean cavities



Jul 21, I942. F, sQmREs APPARATUS FOR FORMING SUB'IERRANEAN CAVITIES Filed Dec, 29, 1938 3 Sheets-Sheet 2 INVENTOR.

s & MMM N a R 5 m m r e JM y 1942- F. sQ'UlRE 2,290,502

' AIPARATUS FOR FORMING SUBTERRANEAN CAVITIES Filed Dec. 29, 1938 3 Sheets-Sheet 5 INVEIYTOR. freaer/ck. 5901/25 5 g 7 L ATTORNEYS.

I BWM Patented July 21, 1942 APPARATUS FOR FORMING SUBTER- RANEAN CAVITIES Frederick Squires, Champaign, The Dow Chemical Company, a corporation of Michigan 111., assignor to Midland, Micln,

Application December 29, 1938, Serial No. 248,187 6 Claims. (Cl. 255-76) This invention relates to a method and apparatus for forming or enlarging a cavity in a water, gas, oil, brine or other type well hole, and more specifically it relates to a method and apparatus for enlarging selected portions of a well hole, or fo ming. or enlarging a cavity in certain selected portions of the well.

This invention is directed to a method and apparatus for forming or enlarging a cavity in certain selected portions of a water, gas, oil or other type well hole, to give a result similar to a shot hole or a hole that has been underreamed or otherwise enlarged. By the practice of this invention' such cavities may be formed at a selected point in the well hole so that there may flow into the cavity, and therein accumulate, the products of the well. This invention enables a cavity of symmetrical form and controllable size to be made disposed about the main well hole, and which is formed without any shock, disruption or fracture to the surrounding formation as would be the case if it were formed by shooting.

With this invention a cavity is formed in the well hole by the action of mechanical cutting teeth, or other cutting and scraping means, the action of which is augmented by a chemical, such as an acid or other agent to dissolve, or partly dissolve, the formation wherein the cavity is to be formed.

The formation of such a cavity in a well hole as v here contemplated, especially when formed in an oil or gas well, will notonly of itself greatly enhance the production of the well, but will serve to condition the well in a manner more favorable for such reconditioning thereof, such as by acidizing and numerous other types of well treatments.

Specifically, it is believed that this invention will find its, or one of its, greatest utilizations in forming or enlarging cavities in those parts of a well hole which are limestone or of other calcareous formation, so that the drainage of the products of the well into the well hole will be greatly assisted and the production of the 'well thereby increased; and additionally a well formed with a cavity by the practice of this invention will be in a materially better condition for any of the various types of acidizing or other chemical treatments.

The principal object of this invention is to provide a method and apparatus for forming, or enlarging a cavity in selected portions of a well hole.

Another object is to provide a mechanical means for forming or enlarging selected portion of a well hole.

Another object is to provide a means for em;

a cavity in a cross-section of a side Fig. 2 taken on line ploying a chemical medium for forming or enlarging a cavity in a selected portion of a well hole.

Another object is to provide mechanical means and a chemical medium for forming or enlarging acavity in a well hole, wherein both said means and medium augment and assist the action and function of the other.

Another object is to provide a method and apparatus for forming, or enlar ing, a cavity in a well hole so that it is of uniform outline, of controllable size and symmetrically disposed about the well hole.

Another object is to form, or enlarge, such a cavity in a well hole so as to assist and increase the production of the well.

Another object is cavity in a well hole so as to facilitate the'reconditioning of the well, as by acidizing, etc.

Still another object is to form, or enlarge, a cavity in a selected portion of a well hole, for

the above and other purposes, in such a manner that the formation in which the cavity is formed or enlarged is not subject to shock, disruption or fracture.

And still another object of this invention is to form such cavities with the aid of hydrochloric acid in that part of a well hole which is at least partly composed of limestone or other calcareous or chemical soluble matter.

Attention is now directed to the drawings illustrating the method and apparatus for practicing this inventio this specification, and wherein:

Fi 1 is a longitudinal view partly in vertical view of one form of apparatus for realizing this invention.

Fig. 2 is a longitudinal view of the apparatus illustrated in Fig. 1, and is a vertical cross-sectional view of a part thereof taken from the front and illustrating certain details thereof.

Fig. 3 is a transverse cross-sectional view of 33 thereof looking in the direction of the arrows.

Fig. 4 is a longitudinal view partly in crosssection of the same apparatus shown in Fig. 1, but here illustrating the apparatus lowered into a well hole and engaged in forming a cavity therein.

Fig. 5 is a transverse cross-sectional view of Fig. 4 taken on line 5-5 thereof.

Fig. 6 is a transverse view partly in crosssection of a detail of Fig. 4'taken on line 66 thereof.

Fig. 7 is a view similar to Figs. 1 and 4 but shows the apparatus starting the forming of a cavity in a well hole.

to form, or enlarge, such a which comprise a part of It is to be clearly understood that this invention relates to both an apparatus and a method for forming or enlarging a cavity, or cavities, in

a well hole, and that while only one general emable it to be lowered into the well hole. The up- ,32 which is pivoted on pin 33 carried by the ear 84 of the shaft head ll, so as to pivotally mount the pipe 3| upon pin it to comprise a third pivot .point C. The joint between pipes 25 and 28,

effected by the elbows 2!.and 21 respectively to comprise pivot point A, and the Joint between pipe 28 and 3|, eflected by the elbow 29 and the T-like fitting 30 to comprise pivot point B, are

"both leakproof pivotal points these pipe connections.

It will be appreciated by reference to Figs. 1, 2,

4 and '7, that pipe II has formed on one side thereof, and preferably in longitudinal alignment, a plurality of stub pipes 15, which are in per end of the housing is formed with a head H provided with a bore l2 passing therethrough in aligrmient with the longitudinal axis of the housing, while the lower end of the housing II is formed with the inwardly projecting annular flange It, the upper surface of whichconstitutes an annular shoulder II. A shaft it, of reduced diameter relativeto that of the housing It and disposed in longitudinal alignment therewith, is capable of limited movement upwardly thereinto, and is provided with a tapered head It. Head I6 is formed with a flange ll adapted to seat upon the shoulder ll of the housing and suspend the shaft from housing l0, and to limit the downward movement of shaft I! therefrom. At the lower end of shaft I! there is formed an annular shoulder l8, adapted upon the upward movement of shaft it, and/or the downward movement of housing II, to contact the flange l3 of housing It and thereby limit the upward movement of the shaft thereinto. Shaft I5 is formed preferably of a length which, from flange II to shoulder I8, is shorter than the distance between the pivot points B and C, the function of which points will hereafter be explained. In the lower end of shaft I! there is formed a circular recess l9 and a similar recess is formed in the topv of the stub shaft or foot 2|. Into these recesses there is fltte the circular dowel pin 22 which is upset at its ndls so as to hold the two shafts together and yet permit independent rotary movement thereof. The shaft or foot 2| may be of any convenient or desiredlength and is provided on the bottom with a series of prongs or anchors 23 for engagement with the bottom of the well hole.

A longitudinal section of the housing ll, ex-

communication with the interior of pipe 3l,-as shown in Fig. 6. With reference to said last mentioned figure it will be seen that in the interior of each'of the stub pipes there is posi- "tioned a disc 36 provided with a plurality of ports, such as the one 31. A stem 38 slidably passes through the center of disc 36 and has formed on its lower end a conical shaped head 39, each of which heads serve as a cutting tooth or scraping member to help form the cavity in the well hole as will be fully appreciated from the following description. The point or cap of head 3! may be formed with a tip 40 of some special material such as will withstand a great amount of wear, such as specially hard steel or a diamond tip. Keyed to the stem 38 is a disc ll adapted to normally be forced by one end of compressed spring 42 against the disc 36 to close and cover the ports therein. The other end of spring 42 abuts against the stop member 43. By this arrangement spring 42 normally maintains the disc 4| in contact with disc 36 and keeps the ports therein closed so that liquid in pipe II cannot escape, but when pressure is appliedto the tip 40 mounted on stem 38, as by the head 39 contacting a solid mass such as the formation in the well hole, then stem 38 is depressed and tending from near the top to near the bottom 7 thereof, is cut away to form therein the .window 24, which is also illustrated in Figs. 4 and 5.

Referring now to Figs. 1 and 2, it will be seen that there is provided a section of pipe or tubing 25, to which may be coupled numerous similar sections or lengths so that they may be made to reach from the surface to permit lowering the housing to any desired depth in the well hole. The pipe extends through the bore 12 formed in head ll of the housing I. and into the housing where it terminates in an elbow 28 which is pivotally connected to elbow 21 to form the pivot point A, which is also shown in Figs. 4 and 7. To elbow 21 is connected a hollow arm or section of pipe 28, which is in communication with pipe 25, and terminates in elbow 29 which makes a pivotal connection with a T-like pipe fitting I. to form the pivot point B. Extending through the fitting 30 there is a pipe orhollow arm'li which is in communication with pipe 22 and is closed at its upper end SI, and has its lower, end II" swaged closed and provided with the hole disc ll is moved upwardly against the action of spring 42 and the ports 31 are uncovered to allow the escape of liquid from pipe 3| and stub pipe 35 through the ports 31. A collar 44 may be positioned on stem-38 adjacent the head 39 to prevent the head from covering the ports 31 when the head is forced inwardly.

With specific reference to Figs. 2 and 3 it will be seen that the pipe section 25 has secured thereto in any convenient manner, as by a key onwelding, a guide 45 which is disposed within the housing II, and which at the ends thereof terminates in flared heads 46 which are slidably mounted in oppodtely disposed grooves or channels 41 formed longitudinally of the interior of housing II and extending substantially the length thereof. By a consideration of Fig. 3 it may more clearly be seen how the guide 45 is secured to the pipe 25 with the heads 48 of the guide disposed in the channels 41 of the housing It. Fig.- 5 likewise illustrates this guide feature, but more specifically with relation to Fig. 4. In Fig. 5 the. guide 45 has slid down the channels 41 until it is at a point opposite a portion of the window 24 formed in the housing "I. I

Pivot points A and C are arranged in vertical alignment, but pivot point B is preferably out of alignment with respect thereto and is caused to be disposed a slight distance to the right of these points by the leaf spring 4! mounted on the in,- terior of housing II which prevents point B from moving into vertical alignment with points And C. Such arrangement assists in causing the pipes-2| and SI to project out of the housing l and into the well hole, as explained.

When it becomes desirable to form a cavity in a well hole, as by the practice of this invention, the apparatus assembly, as illustrated in Fig. l, is lowered into the well hole with the pipes or hollow arms 28 and 3| retracted in the housing I0 which is suitably suspended from the surface by suiiicient lengths of pipe or tubing until it has reached the proper depth opposite the formation in which it is desired to )1'1I1 the cavity or enlarge the hole. During the course of lowering the apparatus into the hole its various parts will maintain their relative positions in the same manner as illustrated in Fig. 1, i. e., the housing H) is suspended from the tube 25 which is kept from pulling out through the top thereof by the guide 45, the shaft I is suspended from the housing I0 by virtue of the engagement made between the flange l1 and the shoulder I4 of these two members respectively, and the foot 2| is connected to and dependent from. the shaft l5. The weight of the entire assembly while being lowered into the well hole is supported by the tube 25.

When the foot 2| strikes the bottom of the hole, the teeth or prongs 23 thereof will dig into the bottom of the hole and at first the weight of will hereinafter be the foot 2| and shaft l5 will be supported on the.

bottom of the hole and as the tube 25 and housing H) are continued to be lowered into the hole the lower end of the housing ID will slide down over the shaft |5 until the flange |3 formed on the housing abuts the shoulder H! of the shaft at which time the weight of the housing is then resting on the foot 2| and they both are then supported by the bottom of the well hole and their. weight is no longer suspended from the tubing 25. It will be well to have interchangeable feet, such as the foot 2|, which are of varying lengths so that the housing may be conveniently supported any desired distance off of the bottom of the well so as to be opposite the formation wherein the cavity is to be formed.

When foot 2| comes to rest on the bottom of the well hole, continued lowering of the tubing 25 will cause guide 45 to slide downwardly in the channel 41 of the housing and also force pipe 28, connected to pipe 25, to move downwardly therewith and pivot at points A and B, and as pipe 3| is stationarily pivoted at point C it will be caused to pivot at points B and C with the result that the two pipes 28 and 3| will be caused to project out of the housing l9 through the window 24 thereof and into the well hole. Such movement of pipes 28 and 3| will result from the above described lowering of pipe 25, as pivot point A is capable of moving only along, or parallel to, the longitudinal axis of the housing by virtue of the guide 45 sliding in channels 41, and as pivot point C is fixed to the head of shaft l5, therefore, only pivot point B is free, but it is free to move in but one direction, namely, to

project out of the housing Ill. The pipe elbow joint 29 and the T-shaped joint 39, constituting pivot point B, are normally in contact with a stop or other abutting member such as the leaf spring 48, secured to the interior of the housing,

outwardly at point B through the window 24 the upper end 3| of pipe 3| will project further out through the window 24 than the pivot point B, and as pipe 3| is connected to this pivot point at a point intermediate its ends, this results in the upper end of pipe 3| and the cutting heads 39 making an initial contact with the wall of the well hole as shown in Fig. 7. When the cutting heads 39 mounted on the upper end of pipe 3| are thus in contact with the well hole wall the apparatus is then in position to commence the forming of the cavity, or similar enlargement, in the formation. This is accomplished by rotating in either direction and by any suitable means from the surface the pipe or tube 25. By virtue of the lower end of tube 25 being con nected to the guide and sliding in'channel 41 it causes the entire housing ID to also rotate.

The pipes 28 and 3| will then revolve in a plane about and substantially horizontal to the vertical axis of pipe 25 and housing l0. As shaft 5 is connected to pipe 3| at point C, the shaft will be caused to rotate, but by virtueof the connection between the foot 2| and shaft I5 effected by "the dowel pin 22, the foot 2| will remain stationary and merely serve to maintain the housing Hi and the pipes therein contained at the desired height from the bottom of the well hole and opposite the formation thereof in which the cavity is to be formed.

When pipe 25 is initially rotated and pipe 3| is in the position shown in Fig. 8, so that the cutting teeth or heads 39 are contacting the wall of the well hole, the resulting planetary movement of the arms 3| then causes the teeth 39 held against the well hole to cut or wear away the wall thereof to form a cavity therein of symmetrical outline. When the cavity is being formed in a calcareous formation of a well hole, there is at this time introduced into pipe 25, from the surface and preferably under pressure, a chemical such as hydrochloric acid of which is designed to maintain pivot point B slightly out of vertical alignment with relation to points Aand C, so that when the pipes 28 and 3| are caused to pivot, as above described,

the pivot point B moves outwardly to project the arms into the well hole.

When the pipes 28 and 3| first pivot and move from about 10 to 25 per cent concentration, or of other suitable strength. The hydrochloric acid is forced down through pipe 25 and into pipes 29 and 3| from whence it will escape throughthe stub pipes 35 and ports 31 of those cutting heads or teeth which are in contact with the well hole wall with sufficient force to depress the heads 39 and uncover the ports 31. In this manner the acid will assist materially in forming the cavity by attacking and dissolving the same. Any other suitable acid or other chemical maybe employed which will dissolve, or partially dis solve, the formation in which the cavity is to be made. For example hydrofluoric acid maybe utilized to form a cavity in siliceous formations.

As the pipe 25 is rotated the pipe or arm 3| and the cutting heads'39 guided thereby will be caused to go round and round against the wall of the well hole constantly wearing and cutting it away by the combined action of the cutting teeth and the chemical employed therewith to act on the formation. If substantial pressure is put on the chemical used to assist the cutting teeth in the formation of the cavity, the formation of such a cavity will proceed more rapidly asthe chemical issues from the ports 31, or such of them as are opened by the action of the teeth 39 contacting the formation of the well hole, in

the form of jets'or streams of acid under pressure. 1

A downward force on pipe 25, applied in any convenient manner from the surface, will cause the cutting heads 39, or at least some of them, to

- the cutting heads 3! to be more effective in their cutting out of the cavity. Such a downward force may be imparted to the tubing 25 as by weighting the same, or by equivalent means, and the force will in turn be imparted-to the arm or pipe 3| to force the teeth into the formation.

Thus it will be seen that only those cutting teeth which are in contact with the formation and engaged in cutting, scraping or otherwise wearing it down to form the cavity therein will be augmented in their cutting action by the escape adjacent thereto of a chemical to assist such forming of the cavity. This is true due to the disc ll normally being held by the spring 42 so as to cover the ports 31 through which the acid, or other chemicals, may escape. Thus in Fig. 7 which represents an initial stage of forming such a cavity, it will be seen that only the top two or three cutting teeth are engaged in cutting away the well hole wall and only adjacent these cutting heads is there a jet or stream of chemical being released.

As the diameter of the cavity becomes greater and greater the pipe or arm 3| will approach a horizontal, or substantially horizontal position, and more and more of the cutting heads 39 will come into play and contact the formation until all, or substantially all, of the cutting heads are at work on the formation, as illustrated in Fig. 4. In this the outline of the cavity shows it to, have been formed to a considerable degree. By this method and apparatus the formation of the cavity progresses gradually and uniformly. The

chemical is released in the form of jets only from the cutting heads actually in contact with the formation and being pressed thereagainst by the force applied on them through pipe 25, and in "this matter, conservation of chemical is maintained.

-,when the cavity has been completely formed, the/ apparatus can be readily removed therefrom by pulling upwardly on pipe 25, which will cause the pipes 28 and 3| to retract within housing I. and to assume their position as shown in Fig. 1, and the entire apparatus can then be removed from the well hole by raising pipe 25 thus bringing the entire assemblyito the surface.

By preliminarily noting on the surface how far pipe 25 has to be depressed downwardly before the hollow arms or pipes 2| and SI are projected through the .window 24 of housing I. to their maximum possible distance, it can be ascertained later when forming the cavity if the same has been formed to a size as large as is possible with the apparatus at hand.

Obviously. in lieu of the cutting heads or teeth as herein illustrated, other types of cutting and/or scraping means may be employed which would still retain the feature of releasing the acid, or other chemical. only when actually in contact with the formation and engaged in forming a cavity therein.

The chemical used in the method may be permitted to escape into the formation or allowed to ascend into the well hole and rise thereinto the surface, or be pumped thereto, and if not then exhausted may be reused.

Other modes ofapplying the principle of my invention may be employed instead of those exsuch stated step or out and distinctly claims or the equivalent of steps be employed.

I therefore particularly point claim as my invention:

1. An apparatus for forminga cavity in a well hole, which comprises a housing member adapted to be introduced into the well hole-to a point adjacent therein where the cavity is to be formed,

a plurality of cutting means carried by said hous-' ing member projectible therefrom and rotatable thereby for forming the cavity, and means for supplying an individual stream of liquid adjacent to each of said cutting means to assist it in forming the cavity only when said means is in cutting engagement with the well hole wall. 7

2. An apparatus for forming a cavity in a well hole, which comprises a string of tubing to be extended into the well hole to a point adjacent therein where said cavity is to be formed, a plurality of individual cutting members suspended by said tubing and .moveable, thereby to form said cavity, and means for introducing a liquid through said tubing and releasing it in individual.

streams adjacent said individual members only when each ofsaid members are actively eng in forming said cavity.

- 3. An apparatus for forming a cavity in a well hole, which comprises a housing adapted to be 'extended'into the well hole to a point adjacent tubing for causing said arm and teeth to revolve in a substantially horizontalplane about the vertical axis of said well hole, and means for releasing a liquid throughsaid arm to those of said teeth actually engaged in cutting away said formation.

4. An apparatus for forming a cavity in a well hole, which comprises a string of tubing adapted to be extended into the well hole to a point adjacent therein where said cavity is to be formed, an arm having cutting teeth mounted thereon pivotally carried by said tubing and projectable thereby into the well hole and in contact with the wall thereof and rotatable thereby in a substantially horizontal plane about the vertical axis of the well hole, and means for releasing a liquid through said arm to those of said cutting teeth actually engaged in cutting away said formation.

'5. A devicefor forming a cavity in a well holeadapted for attachment to the end of a tubing string for lowering into a well, which comprises a tubular housing adapted to be slidably mounted on'the lower end of the tubing string, said housing being open along one side thereof, an anchor shaft extending in slidable relation through 'the lower end of said housing-stop means to I tubing string and in communication therewith, a

plained, change being made as regards the method and apparatus herein disclosed,. 'p'r'ovided the step o stem s ted by a y o t e o ow and lower points are nxedand thecentrai point second tubular arm pivotally connected at its upper end with the lower end of said first arm and in communication therewith, and at its lower end with the upper end of said shaft, forming a series of three pivot points of which the upper is capable of lateral movement in a vertical plane to project through the open side of said housing, a plurality of outwardly facing cutting members arranged lengthwise of said second arm, means for supplying a cutting fluid through the tubing string, and said first arm to the cutting members in said second arm, and means associated with each of said cutting members and actuated by the external pressure thereon to permit flow of cutting fluid to the working face 0! the cutting member.

s. A device according to claim 5.in which the 5 cutting members are each mounted on the valve stem of a valve controlling the flow of fluid to the cutting member.

FREDERICK SQUIRES. 

